In use or processing of various types of materials, including yarns, strands, filaments, strips, etc., all collectively hereinafter being referred to for convenience as a "strip of material", there is a definite need for testing the strip of material to determine certain characteristics thereof, such as coefficient of friction or the proportion of increased tension to original tension. One example of a situation in which this need is particularly acute is in the processing of yarns and like strands into fabrics by knitting machines or other like mechanisms. In the knitting of yarns into fabrics, the tension in the various yarns being fed to the needles of the knitting machines is important since the tension in the yarns will affect the size of the knitted product. Therefore, if the tension in the yarns varies significantly from one product to another, the products will vary in size and sizing problems result. This is only one example of the many problems such variance in tension causes in the use or processing of yarns and similar problems are also encountered with other strips of material.
Since the surface characteristics of the strip of material have a marked effect upon the tension therein, an effective device to test strips of material and to determine the surface characteristics thereof with respect to a surface having characteristics correlated to those surface chracteristics normally encountered by the strips of material in use or processing would obviate many, if not all, of the problems caused by variances in tension due to variances in surface characteristics of the strips of material.
Heretofore, no effective devices or methods have been provided for determining the surface characteristics of strips of material with the accuracy and flexibility of use required. Certain testing devices have been proposed for determining the coefficient of friction of a strip of material, but such devices have invariably suffered from the deficiencies of being usable only in a laboratory or test environment which did not permit their use on strips of material actually moving in use or processing; of being excessively large, complicated, expensive and difficult to use; of requiring an accurate control or measurement of incoming tension; of being not self-balancing; or of being so inaccurate as to be available only to a few or do not give the results desired.